The European Union is looking into whether Elon Musk’s online platform X breached tough new social media regulations in the first such investigation since the rules designed to make online content less toxic took effect.

“Today we open formal infringement proceedings against @X” under the Digital Services Act, European Commissioner Thierry Breton said Monday in a post on the platform formerly known as Twitter.

“The Commission will now investigate X’s systems and policies related to certain suspected infringements,” spokesman Johannes Bahrke told a press briefing in Brussels. “It does not prejudge the outcome of the investigation.”

The investigation will look into whether X failed to do enough to curb the spread of illegal content and whether measures to combat “ information manipulation," especially through its crowd-sourced Community Notes fact-checking feature, were effective.

The 27-nation EU also will examine whether X was transparent enough with researchers and will look into suspicions that its user interface, including for its blue check subscription service, has a “deceptive design.”

“X remains committed to complying with the Digital Services Act, and is cooperating with the regulatory process," the company said in a statement. "It is important that this process remains free of political influence and follows the law. X is focused on creating a safe and inclusive environment for all users on our platform, while protecting freedom of expression, and we will continue to work tirelessly towards this goal.”

A raft of big tech companies faced a stricter scrutiny after the EU's Digital Services Act took effect earlier this year, threatening penalties of up to 6% of their global revenue — which could amount to billions — or even a ban from the EU.

The DSA is a set of far-reaching rules designed to keep users safe online and stop the spread of harmful content that’s either illegal — such as child sexual abuse or terrorism content — or violates a platform’s terms of service, such as promotion of genocide or anorexia.

The EU has already called out X as the worst place online for fake news, and officials have exhorted owner Musk, who bought the platform a year ago, to do more to clean it up. The European Commission, the EU's executive arm, quizzed X over its handling of hate speech, misinformation and violent terrorist content related to the Israel-Hamas war after the conflict erupted.